“We know many customers might not object to having a particular item placed in their mailbox from time to time, but the reasons for restricting use of mailboxes is really two-fold,” said Postmaster Keith Jackson. “First, if there is not enough room in a mailbox due to unauthorized items, the Postal Service can’t deliver the customer’s mail. Secondly, the Postal Service wants to ensure the integrity of our customer’s mailbox. That’s why only Postal Service personnel are authorized to place mail in or remove mail from mailboxes. In fact, U.S. Postal Inspectors advise customers to report people going mailbox to mailbox who are not postal employees. It could be someone completely unaware of the statute placing advertisements, but it could also be someone trying to steal mail.”, While it's technically true that you can refuse any piece of mail, it will only be returned to the office to be recycled. The sender will never know and will not stop sending it. You will only be giving your local carrier more work to do., If the package is delivered while you’re away, you can still refuse it by marking it ‘Refused’ and returning it to the post office or handing it back to the postal carrier during their next visit. The package must remain unopened to qualify for refusal without additional postage costs..